JPWO2020218386A1 - Lubricating oil composition, its manufacturing method and vacuum equipment - Google Patents

Abstract

A lubricating oil composition containing fullerene and a base oil, wherein the fullerene is a sublimated fullerene, and the base oil is a multialkyl cyclopentane oil or an ionic liquid.

Description

The present invention relates to a lubricating oil composition, a method for producing the same, and a vacuum apparatus.
The present application claims priority based on Japanese Patent Application No. 2019-83392 filed in Japan on April 24, 2019, the contents of which are incorporated herein by reference.

Lubricating oil compositions that can be used under high vacuum are required to have properties different from those of ordinary lubricating oil compositions, such as having a low vapor pressure and substantially containing no volatile components.

Patent Document 1 proposes a lubricating oil composition using PFAE (perfluoroalkyl ether), tris (2-octyldodecyl) cyclopentane, or the like having a low vapor pressure as a base oil.

Patent Document 2 describes a selection from an ionic liquid composed of a lithium compound such as bis (trifluoromethanesulfonyl) imidelithium, a nitrogen onium cation, and a weakly coordinated fluorine-containing organic anion or a weakly coordinated fluorine-containing inorganic anion. Antistatic lubricating oil compositions containing the above-mentioned antistatic substances have been proposed.

Patent Document 3 proposes a semi-solid lubricating oil composition composed of an ionic liquid having a low vapor pressure and an antistatic conductivity.

Patent Document 4 describes, as a lubricating oil composition having heat resistance and antioxidant properties, (a) a fluorine-free synthetic oil ^{having a vapor pressure of 1 × 10 -4 Torr or less at 25 ° C., and an ionic liquid.} A lubricating oil composition containing at least one base oil selected from the group consisting of (b) a fullerene compound and at least one selected from the group consisting of by-product carbon particles during the production of fullerenes has been proposed.

Japanese Unexamined Patent Publication No. 10-140169 Japanese Unexamined Patent Publication No. 2005-89667 Japanese Unexamined Patent Publication No. 2005-154755 Japanese Unexamined Patent Publication No. 2005-336309

However, all of these proposals, for example, in the use of lubricating oils used in outer space, place the lubricating oil composition in a harsh environment where it is exposed to high energy rays such as cosmic rays under high vacuum. As a result, it is expected that the physical properties of the lubricating oil composition will change. Therefore, these proposals are not sufficient to maintain stable lubrication performance over a long period of time.
More specifically, the change in the physical properties of the lubricating oil composition occurs because the molecules of the base oil constituting the lubricating oil composition are gradually cleaved and the molecular chain of the base oil is shortened. In particular, in a lubricating oil composition used under a high vacuum, an increase in vapor pressure of the lubricating oil composition occurs due to the formation of a component having a small molecular weight. This increase in vapor pressure causes various problems as described later. This series of changes in the base oil is called "base oil deterioration". Deterioration of base oil may be caused not only by high energy rays but also by heat generation due to frictional wear when an extreme force is applied to a sliding portion.

Due to the increase in vapor pressure due to deterioration of the base oil, a part of the base oil may evaporate and be lost during use, and the lubricating oil may decrease from the sliding portion. As a result, the sliding portion is worn, which may cause seizure. Further, when a part of the base oil evaporates, the lubricating oil also scatters and adheres to a portion other than the sliding portion of the mechanical device, which may contaminate the mechanical device.

Further, in the lubricating oil composition containing fullerene, although the lubrication characteristics were improved, the vapor pressure at the initial stage of use could not be lowered to the same level as the vapor pressure of the base oil. The reason why the vapor pressure at the initial stage of use of the lubricating oil composition is high is considered to be the influence of the residue of the volatile component because a volatile component such as an organic solvent is generally used in the manufacturing process of fullerene.

An object of the present invention is to exhibit excellent wear resistance, have a low vapor pressure, suppress an increase in vapor pressure due to deterioration of base oil, and provide stable lubrication performance for a long period of time even under vacuum. It is an object of the present invention to provide a lubricating oil composition that can be maintained, a method for producing the same, and a vacuum device.

The first aspect of the present invention is the following lubricating oil composition.
[1] Contains fullerenes and base oil,
The fullerene is a sublimated fullerene,
The base oil is a lubricating oil composition which is a multi-alkyl cyclopentane oil or an ionic liquid.
The first aspect of the present invention preferably includes the features described in [2] below.
[2] Further containing a fullerene adduct,
The lubricating oil composition according to the above [1], wherein the fullerene adduct has a structure in which an adduct having a part of the molecular structure constituting the base oil is added to the fullerene.
The second aspect of the present invention is the following method for producing a lubricating oil composition.
[3] The method for producing a lubricating oil composition according to the above [1] or [2].
A method for producing a lubricating oil composition, which comprises a dissolution step of dissolving a fullerene sublimate in a base oil to obtain a fullerene solution.
The second aspect of the present invention preferably includes the features described in the following [4] to [14]. The following features are also preferably combined with each other.
[4] The above-mentioned [3] further comprising a sublimation step of obtaining the fullerene sublimated product by sublimating the raw material fullerene in a non-oxidizing atmosphere to make it a gas and then cooling it to make it a solid before the melting step. ]. The method for producing a lubricating oil composition.
[5] The method for producing a lubricating oil composition according to the above [3] or [4], wherein the fullerene sublimated product contains C ₆₀ , C _{70 or a mixture thereof.}
[6] The method for producing a lubricating oil composition according to any one of [3] to [5] above, further comprising a removing step of removing insoluble components from the fullerene solution after the dissolution step.
[7] The lubricating oil according to any one of [3] to [6] above, further comprising a heat treatment step of heat-treating the fullerene solution in a non-oxidizing atmosphere to form a fullerene adduct after the dissolution step. Method for producing the composition.
[8] The method for producing a lubricating oil composition according to the above [7], wherein the heat treatment temperature in the heat treatment step exceeds the upper limit temperature of the base oil and is in the range of the upper limit temperature of use + 200 ° C. or less.
[9] The method for producing a lubricating oil composition according to the above [7], wherein the heat treatment temperature in the heat treatment step is 150 ° C. or higher and 300 ° C. or lower.
[10] Further having a radiation treatment step of irradiating the fullerene solution with radiation in a non-oxidizing atmosphere to produce a fullerene adduct after the dissolution step.
The method for producing a lubricating oil composition according to any one of the above [3] to [6], wherein the radiation is ultraviolet rays or ionizing radiation.
[11] The method for producing a lubricating oil composition according to the above [10], wherein the radiation is ultraviolet rays having a wavelength of 190 nm or more and 365 nm or less.
[12] The method for producing a lubricating oil composition according to the above [10] or [11], wherein the amount of energy of radiation irradiated in the radiation treatment step is 1 J or more and 100 J or less per 1 mL of the fullerene solution.
[13] The method for producing a lubricating oil composition according to any one of [7] to [12] above, wherein the oxygen partial pressure in the non-oxidizing atmosphere is 10 pascals or less.
[14] In the heat treatment step or the radiation treatment step, the concentration of the fullerene in the fullerene solution is 0.1 times or more and 0.7 times or less the concentration of the fullerene before the heat treatment step or before the radiation treatment step. The method for producing a lubricating oil composition according to any one of the above [7] to [13], which is carried out until the above.
[15] The method for producing a lubricating oil composition according to the above [14], wherein the treatment time of the heat treatment step or the radiation treatment step is 5 minutes or more and 24 hours or less.
A third aspect of the present invention is the following vacuum apparatus.
[16] A vacuum apparatus including the vacuum container, wherein the lubricating oil composition according to the above [1] or [2] is used in the vacuum container.

According to the present invention, it exhibits excellent wear resistance, has a low vapor pressure, suppresses an increase in vapor pressure due to deterioration of base oil, and stably maintains lubrication performance for a long period of time even under vacuum. It is possible to provide a method for producing a lubricating oil composition thereof and a vacuum device that can be maintained.

Hereinafter, the lubricating oil composition and the method for producing the lubricating oil composition according to the embodiment of the present invention will be described. It should be noted that the present embodiment is specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified. Numerical values, order, time, ratio, material, quantity, composition, etc. can be changed, added, omitted, replaced, etc. without departing from the spirit of the present invention.

(Lubricating oil composition)
The lubricating oil composition according to the present embodiment contains fullerene and a base oil, the fullerene is a sublimated fullerene, and the base oil is a multiple alkyl cyclopentane oil or an ionic liquid. Further, the lubricating oil composition of the present embodiment may contain a fullerene adduct, an additive and the like, which will be described later.

(Fullerene sublimation product)
In general, the fullerene production process includes a step of handling the fullerene in a volatile organic solvent, such as extracting the fullerene from soot with an organic solvent such as toluene. Therefore, the molecules of the organic solvent are easily incorporated into the obtained fullerene crystal grains. When such fullerenes are used, volatile components such as molecules of the organic solvent are mixed. Therefore, a lubricating oil composition having a low vapor pressure cannot be obtained. When the above volatile components are contained, for example, when the lubricating oil composition is used in a high vacuum state, the volatile components are volatile. At that time, a part of the base oil and fullerene is also scattered in a liquid state. Therefore, parts other than the sliding parts of the mechanical device are contaminated.

In this embodiment, fullerenes that are substantially free of volatile components are used in order to prevent contamination and contamination. That is, the fullerene contained in the lubricating oil composition of the present embodiment is a fullerene sublimated product. "Fullerene sublimate" refers to a fullerene that is substantially free of volatile components. The method for producing the fullerene sublimated product will be described in detail in the “sublimation step” described later.

Here, when the molecules of the organic solvent are incorporated into the crystal grains of fullerene, the volatile components are also incorporated into the crystal grains. Therefore, it is extremely difficult to quantitatively analyze the volatile components in fullerenes. Therefore, in the present embodiment, a fullerene sample is dissolved in a base oil to prepare a fullerene solution, and the increase in the degree of degassing of the fullerene solution, which will be described later, is substantially 0 (for example, 0.1 or less) as compared with the base oil. ), It can be determined that this sample contains substantially no volatile components.

Examples of the type of fullerene in the fullerene sublimation product include C ₆₀ and C ₇₀ , higher-order fullerenes, and mixtures thereof. _{Among fullerenes, C 60} , C ₇₀ or a mixture thereof is preferable from the viewpoint of high solubility in lubricating oil. A mixture of fullerenes containing 50% by mass or more of _{C 60} is more preferable because the lubricating oil is less colored in brown to black (the deterioration of the lubricating oil composition can be easily determined by color). It may be contained in an amount of 70% by mass or more and 100% by mass or less, and 90% by mass or more and 100% by mass or less. Fullerene sublimate composed only of C ₆₀ is more preferred.
The concentration of the fullerene sublimation product in the lubricating oil composition can be arbitrarily selected, and for example, 0.0001% by mass to 0.010% by mass, 0.0005% by mass to 0.008% by mass, or, if necessary. It is also preferable that it is 0.001% by mass to 0.005% by mass or 0.002% by mass to 0.003% by mass. However, it is not limited to these examples.

(Fullerene adduct)
The lubricating oil composition of the present embodiment may contain a fullerene adduct. The fullerene adduct has a structure in which an adduct having a part of the molecular structure constituting the base oil is added to the fullerene.
The concentration of the fullerene adduct in the lubricating oil composition can be arbitrarily selected, and for example, 0.0001% by mass to 0.010% by mass, 0.0005% by mass to 0.008% by mass, or 0.001% by mass. It is also preferable that it is ~ 0.005% by mass or 0.002% by mass to 0.003% by mass. However, it is not limited to these examples. The concentration of the fullerene adduct may be obtained by any method of choice. For example, as will be described later, it may be estimated from the difference in fullerene concentration before and after the heat treatment.

(Base oil)
The base oil contained in the lubricating oil composition of the present embodiment is an oil having a low vapor pressure. For example, multiple alkylcyclopentane oils and ionic liquids such as Dialkylpiperidin bis (trifluoromethanesulfonyl) imide are preferable.
The base oil preferably does not contain volatile components. Specifically, the vapor pressure of the base oil is preferably 1 pascal or less, more preferably 0.1 pascal or less, and particularly preferably 0.01 pascal or less at 25 ° C. Is preferable.

The molecule of Multiply Alkylated Cyclopentane Oil (hereinafter sometimes referred to as "MAC oil") has a structure in which a plurality of alkyl groups are bonded to a cyclopentane ring. The total number of carbon atoms of these alkyl groups is preferably 48 or more and 112 or less. The total carbon number may be, for example, 48 or more and 60 or less, 48 or more and 80 or less, 70 or more and 112 or less. The carbon number of each alkyl group may be the same or different. The number of alkyl groups bonded to the cyclopentane ring can be arbitrarily selected, and may be, for example, 1 to 5, 2 to 4, or 3 to 4. More specific examples include tris (2-octyldodecyl) cyclopentane in which three alkyl groups having 20 carbon atoms are bonded, tetra (dodecyl) cyclopentane in which four alkyl groups having 12 carbon atoms are bonded, and the like. In addition, a mixture of these is also mentioned. However, it is not limited to these examples.

The ionic liquid is an ionic compound composed of an anion portion and a cation portion, and a liquid at room temperature to 80 ° C. is particularly preferable because it is easy to use.
Examples of the anion portion include bis (trifluoromethanesulfonyl) imide, bis (fluorosulfonyl) imide, diethyl phosphate and the like.
Examples of the cation portion include lithium, cyclohexyltrimethylammonium, ethyldimethylphenylethylammonium, methyltrioctylammonium, 1-aryl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, and 1-butyl-3-methyl. Imidazolium, 1-hexyl-3-methylimidazolium, 1-butyl-2,3-diethylimidazolium, 3,3'-(butane-1,4-zyl) bis (1 vinyl-3-imidazolium), 1-decyl-3-methylimidazolium, 1-butyl-4-methylpyridium, 4-ethyl-4-methylmorofolinium, tetrabutylphosphonium, tributyl (2-methoxyethyl) phosphonium, trihexyl (tetradecyl) phosphonium, Examples thereof include butyl-1-methylpiperidium, 1-butylpyridium, 1-butyl-methylpyrrolidinium, and tributylsulfonium.
Specific examples of the ionic liquid include a compound in which the compound of the cation portion and the compound of the anion portion are appropriately combined. The compound of the cation part and the compound of the anion part to be combined do not have to be one kind, respectively. That is, one or more of the respective compounds may be combined with each other.
The amount of base oil in the lubricating oil composition can be arbitrarily selected. For example, it may be 90.0000% by mass to 99.9999% by mass. However, it is not limited to these examples. )

(Additive)
The lubricating oil composition of the present embodiment contains, in addition to the base oil, the fullerene sublimation product, and the fullerene adduct, an additive that does not substantially contain volatile components as long as the effect as the lubricating oil composition is not impaired. be able to. Examples of the additive include a commercially available antioxidant, a viscosity index improver, an extreme pressure additive, a cleaning dispersant, a pour point lowering agent, a corrosion inhibitor, a solid lubricant, an oiliness improver, a rust preventive additive, and an anti. Examples thereof include emulsifiers, antifoaming agents and hydrolysis inhibitors. These additives may be used alone or in combination of two or more. The amount of additive can be arbitrarily selected.

Examples of the antioxidant include butylhydroxyanisole (BHA), dialkyldiphenylamine and the like.

Examples of the viscosity index improver include polyalkylstyrene and hydride additives of styrene-diene copolymer.

Examples of the extreme pressure additive include dibenzyl disulfide, allyl phosphate ester, allyl subphosphate ester, amine salt of allyl phosphate ester, allyl thiophosphate ester, amine salt of allyl thiophosphate ester and the like.

Examples of the cleaning dispersant include benzylamine succinic acid derivatives, alkylphenol amines and the like.
Examples of the pour point lowering agent include chlorinated paraffin-naphthalene condensate, chlorinated paraffin-phenol condensate, polyalkylstyrene type and the like.

Examples of the anti-emulsifier include alkylbenzene sulfonate and the like.

Examples of the corrosion inhibitor include dialkylnaphthalene sulfonate and the like.

(Manufacturing method of lubricating oil composition)
The method for producing a lubricating oil composition of the present embodiment includes a dissolution step of dissolving the fullerene sublimation product in the base oil to obtain a fullerene solution. The fullerene solution obtained in this step may be used as it is as a lubricating oil composition, but as will be described later, a further processed fullerene solution may be used as a lubricating oil composition.

As described above, the fullerene sublimated product used in the dissolution step _{preferably contains C 60} , C ₇₀ or a mixture thereof from the viewpoint of high solubility in lubricating oil. A mixture of fullerenes containing 50% by mass or more of _{C 60} is more preferable because the lubricating oil is less colored. Fullerene sublimate consists of C ₆₀ is more preferred.

The concentration of fullerene in the fullerene solution is arbitrarily selected, but is preferably, for example, 1% by mass (0.0001% by mass) or more and 100% by mass (0.01% by mass) or less, and 3% by mass (0. It is more preferably 0003 mass%) or more and 75 mass ppm (0.0075 mass%) or less, and further preferably 5 mass ppm (0.0005 mass%) or more and 50 mass ppm (0.005 mass%) or less. preferable. The concentration of fullerenes may be measured by an arbitrarily selected method, for example, a method using high performance liquid chromatography (HPLC).

The dissolution in the above-mentioned dissolution step can be carried out by an arbitrary selection method, and preferably can be carried out by ordinary mechanical stirring, ultrasonic stirring or the like. The temperature may be agitated at room temperature if the base oil is a low viscosity liquid at room temperature. On the other hand, when the base oil is a highly viscous liquid or solid at room temperature, it is preferable to heat it to a low-viscosity liquid state and stir to dissolve it. The stirring time may be arbitrarily selected.

(Sublimation process)
The fullerene sublimation product used in the melting step may be a commercially available product, or may be produced from ordinary fullerene (raw material fullerene) by providing a sublimation step. That is, in the method for producing the lubricating oil composition, before the dissolution step, the raw material fullerene is sublimated in a non-oxidizing atmosphere to form a gas, and then cooled to form a solid to obtain the fullerene sublimated product. It may further have a sublimation step. For example, the fullerene sublimated product can be obtained by sublimating the raw material fullerene into a gas in a non-oxidizing atmosphere having an oxygen gas partial pressure of 10 pascals or less and then cooling the raw material fullerene into a solid. The raw material fullerene may mean fullerene not obtained in the sublimation step, and a commercially available product may be used.
By providing the above sublimation step, the melting step can be continuously performed after the sublimation step. This method is preferable from the viewpoint of preventing the mixing of volatile components from the air or the like by avoiding the storage of the obtained fullerene sublimated product.

In the sublimation step, specifically, for example, a commercially available sublimation purification apparatus can be used to sublimate the raw material fullerene. As an example of sublimation, first, the raw material fullerene is arranged in a heating part inside the sublimation purification apparatus, and in this state, the inside of the apparatus is depressurized to reduce the partial pressure of oxygen gas to 10 pascals or less. By heating the heating section after depressurization, the raw material fullerene in the heating section undergoes a phase change from a solid to a gas. After that, the phase changes from gas to solid by cooling, and precipitates as a fullerene sublimate. According to this method, since the raw material fullerene is once in a gas molecular state, the volatile component in the state contained in the crystal of the raw material fullerene can be removed. The fullerene sublimated product thus obtained does not substantially contain the above-mentioned volatile components. Therefore, by providing the sublimation step, a lubricating oil composition having a low vapor pressure can be obtained.

(Removal process)
The fullerene solution obtained in the dissolution step may contain insoluble fullerenes and the like. In that case, it is preferable to remove these insoluble components. That is, the method for producing the lubricating oil composition may further include a removing step of removing the insoluble component from the fullerene solution after the dissolving step. The method for removing the insoluble component can be arbitrarily selected, and examples thereof include a method of filtering using a membrane filter, a method of sedimentation removal using a centrifuge, and a method of using both of these methods in combination. ..

(Heat treatment process / Radiation treatment process)
The fullerene adduct can be obtained by heat-treating or radiation-treating the fullerene solution in a non-oxidizing atmosphere such as lowering the oxygen partial pressure. That is, the method for producing the lubricating oil composition may further include a heat treatment step of heat-treating the fullerene solution in a non-oxidizing atmosphere to form the fullerene adduct after the dissolution step. Further, after the dissolution step, a radiation treatment step of irradiating the fullerene solution with radiation in a non-oxidizing atmosphere to produce the fullerene adduct may be further provided.

The fullerene adduct may be obtained by performing one or both of the heat treatment step and the radiation treatment step, or the fullerene adduct may be obtained by performing both the heat treatment step and the radiation treatment step at the same time.

By performing such a treatment, a part of the molecular structure constituting the base oil is cleaved, and as a result, a highly reactive molecule (hereinafter referred to as “cleaving molecule”) is generated, which is added to fullerene. , Produces a fullerene adduct. In this case, the fullerene adduct obtained by this treatment has a structure in which an adduct having a part of the molecular structure constituting the base oil is added to the fullerene. An excellent effect can be obtained by producing the fullerene adduct.

The change of fullerene into a fullerene adduct can be confirmed by measuring the mass spectrum of the fullerene solution before and after the treatment. _{For example, when C 60} is used as the fullerene sublimation product, only the peak of m / z = 720 corresponding to _{C 60} is confirmed in the lubricating oil composition before heat treatment or radiation treatment. On the other hand, in the treated lubricating oil composition, the peak of 720 is reduced and a plurality of peaks of the fullerene adduct appear. As the main peak, a peak (722 + 2N) corresponding to _{C 60} to which a plurality of alkyl groups having different chain lengths are added can be confirmed. N is a natural number of 60 or less. This is what two molecules of the alkyl radicals generated by cleavage of the base oil was added to the C _60.

Since the molecule of the base oil does not necessarily cleave at a specific site, the fullerene adduct usually does not become a single type of molecule, and its analysis becomes difficult. Therefore, as for the progress of the reaction in which the fullerene adduct is formed, it is advisable to measure the concentration of the remaining fullerene and use the fullerene residual rate represented by the following formula as a guide.
(Fullerene residual rate) = [Fullerene concentration after treatment] / [Fullerene concentration before treatment]
In the above formula, the treatment means one or both of heat treatment and radiation treatment. In addition, when determining the fullerene residual rate during the treatment, the above-mentioned "fullerene concentration after treatment" may be read as "fullerene concentration during treatment". In addition, the fullerene concentration can be measured by a method using high performance liquid chromatography (HPLC) described in Examples.
The concentration of the produced fullerene adduct may be estimated by the following formula.
[Fullerene adduct concentration] ≒ [Fullerene concentration before treatment]-[Fullerene concentration after treatment]

The fullerene residual ratio determined by the above formula is preferably 0.1 or more and 0.7 or less, and more preferably 0.2 or more and 0.5 or less. When the residual ratio of fullerene is 0.1 or more and 0.7 or less, the lubricity of the lubricating oil composition is more stably developed from the initial stage of use, frictional wear of sliding parts of mechanical devices is suppressed, and base oil is used. It is possible to suppress the generation of volatile components due to deterioration.

Therefore, in the present embodiment, the fullerene concentration of the fullerene solution is monitored during the heat treatment step or the radiation treatment step, and the fullerene concentration is 0.1 or more and 0 or more with respect to the concentration of the fullerene before the heat treatment step or the radiation treatment step. It is preferable to carry out until it becomes 0.7 or less. The treatment time of the heat treatment step or the radiation treatment step can be arbitrarily selected, but it is preferably 5 minutes or more and 24 hours or less, which facilitates the heat treatment or radiation treatment operation. As an adjustment of the treatment time, for example, if the heat treatment temperature is raised or the radiation irradiation intensity is increased, the treatment time can be shortened, and conversely, if the heat treatment temperature is lowered or the radiation irradiation intensity is lowered, the treatment time can be lengthened. can. Further, in the radiation treatment step, the radiation intensity, the irradiation time, and the number of irradiations may be arbitrarily selected. For example, a method in which the fullerene concentration is within the range by adjusting the number of irradiations, such as repeating irradiation of radiation with a certain high radiation intensity for a short time (about 0.1 seconds or more and 3 minutes or less) about 2 to 10 times. Is also easy to operate and preferable.

Fullerene solutions are usually handled in the atmosphere. Therefore, the oxygen gas concentration in the solution is in equilibrium with the oxygen gas in the atmosphere. In addition, the oxygen molecule reacts with the cleaving molecule and suppresses the formation of the fullerene adduct. Therefore, it is preferable to remove oxygen molecules in the fullerene solution as much as possible and perform heat treatment or radiation treatment in a non-oxidizing atmosphere. As the non-oxidizing atmosphere in the heat treatment step or the radiation treatment step, the oxygen partial pressure in the non-oxidizing atmosphere is preferably 10 pascals or less in a gas phase in equilibrium with the fullerene solution, and is 5 pascals or less. More preferably, it is more preferably 2 pascals or less. It may be 1 pascal or less or 0.1 pascal or less. Further, as an example of the non-oxidizing atmosphere, the inert gas atmosphere as described below is preferably mentioned. Specific examples of the heat treatment process include the following two methods, and specific examples of the radiation treatment process include the following one method.

-Heat treatment step The heat treatment temperature is preferably a temperature exceeding the upper limit of the operating temperature of the base oil. When the upper limit temperature of the base oil is exceeded, cleaving molecules are likely to be generated. In addition, higher temperatures generate more cleaving molecules, resulting in shorter heat treatment times. From the viewpoint of the heat treatment time that is easy to operate, the heat treatment temperature in this heat treatment step is preferably in the range of exceeding the upper limit temperature of use of the base oil and not more than the upper limit temperature of use of the base oil + 200 ° C. The upper limit temperature of the base oil can be known from the catalog of the base oil manufacturer. The upper limit temperature for use may mean the upper limit of the temperature of the base oil, which enables the base oil to be used relatively stably. When the upper limit temperature for using the base oil is unknown, as a guide, the heat treatment temperature is preferably 150 ° C. or higher and 300 ° C. or lower, and more preferably 200 ° C. or higher and 250 ° C. or lower. The time of the heat treatment step can be arbitrarily selected, but is preferably 5 minutes to 24 hours. It may be 5 minutes to 30 minutes, 30 minutes to 1 hour, 1 hour to 5 hours, 5 hours to 24 hours, and the like. However, it is not limited to these examples.

The method for creating a non-oxidizing atmosphere can be arbitrarily selected. For example, the fullerene solution is placed in an airtight metal container such as stainless steel, and then the container is sealed. Next, the inside of the container is replaced with an inert gas such as nitrogen gas or argon gas, or the fullerene solution in the container is bubbled with the inert gas. In this way, the fullerene solution is brought into equilibrium with the inert gas, and the oxygen partial pressure is set to 10 pascals or less.

Alternatively, as a method of creating a non-oxidizing atmosphere, a method of reducing the pressure inside the airtight container can be mentioned. For example, if the pressure inside the container is reduced to 10 pascals or less, the oxygen partial pressure of the gas phase can be 10 pascals or less, usually 2 pascals or less. The fullerene solution can be heat-treated by creating a non-oxidizing atmosphere in the container by reducing the pressure in this way and heating the container while maintaining that state.

The heating of the fullerene solution can be carried out by any method of choice. For example, it can be heated from the outside in an oil bath or the like, irradiated with infrared rays, or irradiated with microwaves.
Further, in the heat treatment step, the fullerene residual ratio may be confirmed every time a certain period of time elapses, and heating (heat treatment) may be continued until a desired fullerene residual ratio is obtained.

-Radiation treatment process The radiation used for the above radiation treatment is radiation that has the energy to generate cleaving molecules. Specifically, it is ultraviolet rays or ionizing radiation, preferably ultraviolet rays. More preferably, it is ultraviolet rays having a wavelength of 190 nm or more and 365 nm or less, and even more preferably ultraviolet rays having a wavelength of 330 mn or more and 350 nm or less. For example, the CC single bond is cleaved by ultraviolet light having a wavelength of 341 nm or less. Further, when the radiation irradiation treatment is performed at room temperature, thermal vibration is superimposed, so that the CC single bond is cleaved even by ultraviolet rays having a wavelength slightly longer than 341 nm. Therefore, by irradiating ultraviolet rays having a wavelength of 190 nm or more and 365 nm or less, cleavage molecules can be sufficiently generated. Also, as long as cleaving molecules can be generated, low-energy radiation has a limited number of binding sites that cleave in the base oil molecule. Therefore, it tends to be a large cleaving molecule that retains the partial shape of the molecule of the original base oil, and it is considered that the affinity of the obtained fullerene adduct with the base oil is improved.

Similar to the above heat treatment, the radiation treatment is preferably performed in a non-oxidizing atmosphere. However, when irradiating with radiation, a radiation source such as an ultraviolet lamp is inserted into the container, or at least a part of the container is made of a material through which the radiation to be used is transmitted in order to irradiate from the outside of the container. Use what you have. For example, when irradiating with ultraviolet rays, the whole or a part of the above-mentioned stainless steel container can be replaced with a material that allows ultraviolet rays to pass through, such as quartz glass.

The amount of energy of the radiation irradiated in the radiation treatment step can be arbitrarily selected, but 1 J or more and 100 J or less is preferable, 1.5 J or more and 60 J or less is more preferable, and 2 J or more and 20 J or less is further preferable, per 1 mL of the fullerene solution. It may be 1J or more and 10J or less, 1J or more and 8J or less. Within this range, it is easy to adjust the range of the concentration of fullerene after the treatment obtained from the above formula, that is, the residual rate of fullerene to 0.1 or more and 0.7 or less. As described above, the irradiation may be performed only once, or may be divided into two or more times and performed a plurality of times. Irradiation may be performed under the same conditions. When the irradiation is divided into a plurality of times, it is preferable that the total energy amount of the radiation is within the above range. The number of irradiations can be arbitrarily selected, and may be in the range of 1 to 10 times or 2 to 5 times, for example. However, it is not limited to these examples. It is also preferable to check the fullerene residual rate each time the irradiation is performed and repeat the irradiation one or more times until the desired fullerene residual rate is obtained.
In the case of ultraviolet irradiation, ordinary low-pressure mercury lamps, UV ozone lamps, ultraviolet LEDs, excimer lamps, xenon lamps and the like can be used. As the ultraviolet irradiation amount, the energy density (mW / cm ² ) of the ultraviolet irradiation light is measured in advance using an ultraviolet photometer, and then the irradiation time (seconds) and the irradiation range (cm ² ) are specified. do. From these things, the energy amount (J) of the ultraviolet rays to irradiate can be determined. The irradiation time can be arbitrarily selected. For example, it may be 5 minutes or more and 24 hours or less. Alternatively, it may be 0.1 seconds to 1 hour, 0.2 seconds to 30 minutes, 0.3 seconds to 3 minutes, 0.5 seconds to 60 seconds, or 1 second to 30 seconds.

According to the lubricating oil composition of the present embodiment, not only the frictional resistance is reduced and the abrasion resistance is excellent, but also the vapor pressure can be low, and the generation of volatile components due to the deterioration of the base oil is suppressed. , The increase in vapor pressure of the lubricating oil composition can be suppressed. The lubricating oil composition of the present embodiment can be used for various purposes, but is particularly suitable for use in vacuum or in outer space.
Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various aspects of the present invention are described within the scope of the claims. It can be transformed and changed.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

[Example 1]
(Preparation of lubricating oil composition)
First, C ₆₀ as a raw material fullerene _{(manufactured} by Frontier Carbon Corporation Nanomu ^TM purple ST) 10 g, sublimation purification apparatus (Asahi Seisakusho Co., Ltd., a small sublimation purification apparatus) by sublimation were used to obtain fullerene sublimate. Sublimation of the raw material fullerene was carried out in a three-zone system. The high temperature zone was 700 ° C., the medium temperature zone was 200 ° C., the low temperature zone was room temperature, and the pressure in each zone was 10 pascals or less. The raw material fullerene was placed in the high temperature zone to change the phase from solid to gas, and the fullerene sublimated product which changed phase from gas to solid and became solid was recovered from the medium temperature zone.

In the sublimation operation, the raw material fullerenes were placed at room temperature, the pressure was reduced in each zone until the pressure became 10 pascals or less, and then the high temperature zone and the medium temperature zone were simultaneously raised to a constant temperature at a rate of 10 ° C./min. Sublimation of fullerenes began when the temperature in the high temperature zone exceeded 600 ° C., and the pressure during sublimation was 10 pascals or less.

Next, 0.001 g of the obtained fullerene sublimated product and 10 g of tris (2-octyldodecyl) cyclopentane (manufactured by Nye Lubricants, synthetic oil 2001A), which is a MAC oil, were mixed as a base oil. The resulting mixture was stirred at room temperature using a stirrer for 36 hours. Next, this was filtered through a 0.1 μm mesh membrane filter to obtain a fullerene solution. As a result of measuring the fullerene concentration of the obtained fullerene solution, it was 100 mass ppm. The obtained fullerene solution was used as a lubricating oil composition.

A high performance liquid chromatograph (1200 series manufactured by Agilent Technologies) was used to measure the concentration of the fullerene. Specifically, in this apparatus, a column YMC-Pack ODS-AM (150 mm × 4.6) manufactured by YMC Co., Ltd. is used, and a 1: 1 (volume ratio) mixture of developing solvent: toluene and methanol is used for absorbance. The amount of fullerene in the sample such as the lubricating oil composition was quantified by detecting at (wavelength 309 nm). The calibration curve was prepared from the above-mentioned raw material fullerene.

(Evaluation of wear resistance)
The abrasion resistance of the obtained lubricating oil composition was evaluated using a friction and wear tester (Ball-on-disc tribometer manufactured by Antonio Par).
First, a substrate and balls were prepared, and these materials were high carbon chrome bearing steel SUJ2. The diameter of the ball was 6 mm. The lubricating oil composition was applied to one main surface of the substrate, and the substrate was heated to 100 ° C. Next, the fixed ball was slid on one main surface of the substrate via the lubricating oil composition by rotating the substrate so that the ball would draw a circular trajectory on the substrate. The velocity of the ball on one main surface of the substrate was 5 cm / sec, and the load of the ball on one main surface of the substrate was 10 N. The rubbing surface (circular) of the ball surface when the sliding distance of the ball on the one main surface of the substrate was 300 m in total was observed with an optical microscope. The diameter of the rubbing surface formed on the ball was measured, and this value was taken as the wear resistance. It can be said that the smaller the diameter of the rubbing surface, the better the wear resistance. The results are shown in Table 1.

(Evaluation of stability)
The presence or absence of components volatilized from the lubricating oil composition under high vacuum was measured using a heated desorption gas analyzer (TPDtype V manufactured by Rigaku). For 0.01 g of the lubricating oil composition, the degree of degassed gas at an ^{atmospheric pressure of 10-5 pascal was measured.} The degree of desorption gas was set as an integrated value of peaks having a molecular weight of 46 or more and 200 or less in order to eliminate the influence of molecules having a molecular weight smaller than that of carbon dioxide (molecular weight 44). As a comparative product, the same measurement was carried out using a MAC oil to which trimethylbenzene (TMB) (manufactured by Tokyo Kasei Co., Ltd.) was added in an amount of 1 mass ppm as a volatile component. In MAC oil to which TMB was added, a peak caused by TMB was detected. The integrated value of this peak was set to 1 (reference value). The ratio of the integrated value of the peaks caused by the desorbed gas of the measured lubricating oil composition to this reference value was defined as the desorbed gas degree. It can be said that the smaller the degree of desorption gas, the better the stability under high vacuum.

The degree of desorption gas was measured at two points, before the wear resistance test and after the wear resistance test. In the above wear resistance test, the metal comes into direct contact with the metal and generates heat, which breaks the molecular chain of the base oil and deteriorates it. As a result of the deterioration, some of the cleaved molecules are detected as volatile components by the above method. That is, a lubricating oil having poor wear resistance is not preferable because the amount of the desorbed gas component increases because the deterioration of the base oil progresses. The results are shown in Table 1.

[Comparative Example 1]
A lubricating oil composition was obtained in the same manner as in Example 1 except that the raw material fullerene (without the sublimation step) was used as it was instead of the fullerene sublimated product. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

[Comparative Example 2]
A lubricating oil composition was obtained in the same manner as in Example 1 except that fullerene was not added to the MAC oil. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

From Table 1, it was found that in Example 1, when a fullerene sublimated product was dissolved in MAC oil to obtain a fullerene solution (lubricating oil composition), the diameter of the rubbing surface was 200 μm and the wear resistance was excellent. Further, the degree of degassing of the lubricating oil composition before the abrasion resistance test is 0.1, the vapor pressure of the lubricating oil composition at the initial stage of use is low, and the stability under high vacuum at the initial stage of use is excellent. Do you get it. Furthermore, it was found that the degree of degassing of the lubricating oil composition after the abrasion resistance test was 0.9, the increase in vapor pressure due to deterioration of the base oil was suppressed, and the stability under high vacuum was excellent.

Further, when Example 1 and Comparative Example 1 were compared, the wear resistance was the same, but in Example 1, the degree of desorption gas before and after the wear resistance test was superior to that of Comparative Example 1. This is because the sublimated fullerene (fullerene sublimated product) does not substantially contain volatile components, and by adding the fullerene sublimated product to MAC oil, the volatile components contained in the lubricating oil composition are suppressed, and the volatile components are suppressed. As a result, it is presumed that the amount of desorbed gas could be minimized.

Further, when Example 1 and Comparative Example 2 were compared, the degree of degassing before the wear resistance test was as good as that, but in Comparative Example 2, the wear resistance was lowered and after the wear resistance test. The degree of degassing was significantly inferior. From this, it was found that by adding the fullerene sublimate to the MAC oil, the wear resistance was improved, and as a result, the increase in the amount of degassing was suppressed.

[Example 2]
A lubricating oil composition was obtained in the same manner as in Example 1 except that the fullerene solution (lubricating oil composition) obtained in Example 1 was irradiated with ultraviolet rays. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

The ultraviolet irradiation in Example 2 was carried out by the following procedure. First, 3 ml was taken out into a quartz cell with a septum cap (manufactured by Tokyo Glass Instruments Co., Ltd., S15-UV-10).
Next, insert two injection needles into the septum cap of the quartz cell, and flow 99.99% pure nitrogen gas (partial pressure of gas other than nitrogen at normal pressure is 10 pascals or less) at 60 mL / min for 10 minutes. bottom. Next, the fullerene solution contained in the quartz cell was intermittently irradiated with ultraviolet rays.
An ultraviolet irradiation device (Omnicure S2000 manufactured by Sanei Tech Co., Ltd.) was used for ultraviolet irradiation. Specifically, the filter is 250 nm-450 nm, the irradiation range is 2 cm ^{2, and the output is adjusted to 1 W / cm 2} while measuring with an ultraviolet illuminometer (wavelength 230 nm-390 nm), and the irradiation timer is set to 1 second. It was set so that 2 J (0.7 J per 1 mL of fullerene solution) of energy could be irradiated with one irradiation.

Next, after each irradiation with ultraviolet rays, about 0.01 ml of the fullerene solution was withdrawn from the inside of the quartz cell using a syringe, and the fullerene concentration was measured by high performance liquid chromatography (HPLC) to determine the fullerene residual rate.
The fullerene residual rate was 0.55 after two ultraviolet irradiations (1.3 J per 1 mL of fullerene solution). Therefore, the ultraviolet irradiation was stopped, and the contents were taken out from the quartz cell to obtain a lubricating oil composition. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 55 mass ppm, and the fullerene residual ratio was 0.55. The results are shown in Table 1.

Further, with respect to the fullerene solution (lubricating oil composition of Example 1) before irradiation with ultraviolet rays and the lubricating oil composition of Example 2 obtained after irradiation with ultraviolet rays, a mass spectrometer (manufactured by Agilent Technologies, LC / MS, Using 6120), component analysis with a molecular weight of 720 or more and 2000 or less was performed. In the fullerene solution before UV irradiation of Example 1, a fullerene peak 720 was mainly observed, and a plurality of other peaks considered to be caused by the base oil were observed. In the lubricating oil composition after UV irradiation of Example 2, in addition to the above-mentioned peaks, m / z = 750, 764, 766, 778, 780, 792, 794, 796, 808, 806, 820 are the main peaks. , 834 peaks were newly confirmed. From these facts, it was confirmed that the fullerene solution (lubricating oil composition) after the irradiation with ultraviolet rays contained the fullerene and the formed fullerene adduct. In the other Examples and Comparative Examples, the fullerene solutions before and after the heat treatment or the radiation treatment were analyzed in the same manner. As a result, no fullerene adduct was confirmed in the fullerene solution before the heat treatment or radiation treatment, but the fullerene adduct was confirmed after these treatments.

[Example 3]
Instead of irradiating with ultraviolet rays, a fullerene solution in a quartz cell was immersed in an oil bath at 200 ° C. and heated. A lubricating oil composition was obtained in the same manner as in Example 2 except that it was heated instead of ultraviolet irradiation. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

In the heating of Example 3, about 0.01 ml of the fullerene solution was withdrawn from the inside of the quartz cell every 5 minutes using a syringe, and the fullerene concentration was measured by HPLC to determine the fullerene residual ratio. The fullerene residual rate was 0.2 15 minutes after the start of the measurement. To this end, the quartz cell was removed from the oil bath and cooled to room temperature to give a lubricating oil composition. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 15 mass ppm, and the fullerene residual ratio was 0.15.

As shown in Table 1, in Example 2, when the fullerene sublimate was dissolved in MAC oil to obtain a fullerene solution and the fullerene solution was irradiated with ultraviolet rays twice, the diameter of the rubbing surface was 160 μm. The degassing degree of the lubricating oil composition before and after the abrasion resistance test was 0.1 and 0.5, respectively. That is, it was found that the wear resistance and the stability under high vacuum were more excellent. Similarly, in Example 3, when a fullerene sublimate was dissolved in MAC oil to obtain a fullerene solution and the fullerene solution was heat-treated, the diameter of the rubbing surface was 155 μm, and the lubricating oil before and after the wear resistance test. The degassing degree of the composition was 0.1 and 0.3, respectively. That is, it was found that the wear resistance and the stability under high vacuum were more excellent.

Further, comparing Examples 2 and 3 in which ultraviolet irradiation or heating was performed as a step of producing the fullerene adduct and Example 1 in which the ultraviolet irradiation or heating was not performed, Examples 2 and 3 have abrasion resistance. , And both the degree of desorption gas before the wear resistance test and after the wear resistance test were excellent. This means that the fullerene adduct is produced in the fullerene solution by the above-mentioned fullerene adduct formation step, and as a result, the wear resistance is increased, and the wear resistance is increased to minimize the amount of volatile components. It is presumed that it was possible.

[Example 4]
A lubricating oil composition was obtained in the same manner as in Example 2 except that the fullerene solution was irradiated with ultraviolet rays eight times. In Example 4, the fullerene residual rate was 0.25 after 8 times of ultraviolet irradiation (5.3 J per 1 mL of fullerene solution). Therefore, the ultraviolet irradiation was stopped, and the contents were taken out from the quartz cell to obtain a lubricating oil composition. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 25 mass ppm, and the fullerene residual ratio was 0.25. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

As shown in Table 1, in Example 4, when the fullerene solution was irradiated with ultraviolet rays eight times, the diameter of the rubbing surface was 155 μm, and the degree of degassing of the lubricating oil composition before and after the wear resistance test. Was 0.1 and 0.3, respectively. That is, it was found that the wear resistance and the stability under high vacuum were more excellent.

Further, comparing Example 4 and Example 2, in Example 4, both the wear resistance and the degree of desorption gas after the wear resistance test were superior to those in Example 2. Examples 2 and 4 have the same conditions except that the number of times of ultraviolet irradiation is different. Therefore, in Example 2 and Example 4, it is estimated that the cleaved molecular species (additive groups of the fullerene adduct) produced are almost the same, and the difference is that Example 4 has a lower fullerene residual rate than Example 2, that is, In Example 4, more fullerene adducts are produced. Due to this difference, it is presumed that in Example 4, the wear resistance was improved, and as a result, the degree of desorbed gas after the wear resistance test was also lowered.

[Example 5]
Example 1 and Example 1 except that a low-pressure mercury UV lamp (Sen Special Light Source Co., Ltd., model UVL20PH-6, including ultraviolet rays of 185 nm and 254 nm as light wavelength components) was used as a light source of radiation, and irradiation was used for 20 seconds. Similarly, a lubricating oil composition was obtained. Here, the irradiation range was 5 cm ² , and the output was 0.2 W / cm ² . That is, the lubricating oil composition was irradiated with 20 J (7 J per 1 mL of fullerene solution) of ultraviolet rays by irradiation for 20 seconds. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 22 mass ppm and the fullerene residual ratio was 0.22. Table 1 shows the results of the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

[Example 6]
A lubricating oil composition was obtained in the same manner as in Example 1 except that X-ray irradiation was performed for 480 seconds using an X-ray irradiation device (RIX-250C-2 manufactured by Torrec Co., Ltd.) as a light source of radiation. rice field. As a result of measuring the fullerene concentration of the obtained lubricating oil composition, it was 20 mass ppm and the fullerene residual ratio was 0.20. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

Comparing Example 5 and Example 4, both were irradiated with ultraviolet rays, and as a result, the fullerene residual rate was reduced to the same extent. However, in Example 4, the degree of degassed gas after the wear resistance and the wear resistance test was superior to that of Example 5. It is presumed that this is because, in Example 5, the ultraviolet rays contain light of 185 nm (far ultraviolet rays).

Comparing Example 6 and Example 5, both were irradiated with radiation, and as a result, the fullerene residual rate was reduced to the same extent. However, in Example 6, the degree of degassed gas after the wear resistance and the wear resistance test was inferior to that of Example 5. It is presumed that this is because X-rays having higher energy than ultraviolet rays were used as radiation in Example 6.

[Example 7]
The lubricating oil composition was prepared in the same manner as in Example 1 except that the ionic liquid 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (LiTFSI manufactured by Tokyo Kasei Co., Ltd.) was used as the base oil. Obtained. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

[Comparative Example 3]
A lubricating oil composition was obtained in the same manner as in Example 7 except that the raw material fullerene (without the sublimation step) was used as it was instead of the fullerene sublimated product. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

Comparing Example 7 and Comparative Example 3, the desorption gas degree before and after the wear resistance test was superior in Example 7 using the fullerene sublimated product.

[Example 8]
A lubricating oil composition was obtained in the same manner as in Example 3 except that the ionic liquid 1-decyl-3-methyl-imidazolium bis (trifluoromethanesulfonyl) imide (manufactured by Tokyo Kasei) was used as the base oil. .. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 12 mass ppm and the fullerene residual ratio was 0.12. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

[Example 9]
A lubricating oil composition was obtained in the same manner as in Example 4 except that the ionic liquid 1-decyl-3-methyl-imidazolium bis (trifluoromethanesulfonyl) imide (manufactured by Tokyo Kasei) was used as the base oil. .. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 35 mass ppm and the fullerene residual ratio was 0.35. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

The comparison results of Examples 8 and 9 and Example 7 showed the same tendency as the comparison results of Examples 3 and 4 and Example 1 described above. That is, it was found that the ultraviolet irradiation treatment and the heat treatment are effective from the viewpoint of the wear resistance effect and the reduction of degassing even in different base oils.

[Example 10]
A lubricating oil composition was obtained in the same manner as in Example 1 except that 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide, which is an ionic liquid, was used as a base oil. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

[Comparative Example 4]
A lubricating oil composition was obtained in the same manner as in Example 10 except that the raw material fullerene (without the sublimation step) was used as it was instead of the fullerene sublimated product. Table 1 shows the results of wear resistance and desorption gas degree of the obtained lubricating oil composition.

Comparing Example 10 and Comparative Example 4, the degree of desorption gas before and after the wear resistance test was superior to that of Comparative Example 5 in Example 10 using the fullerene sublimated product.

[Example 11]
A lubricating oil composition was obtained in the same manner as in Example 3 except that 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide, which is an ionic liquid, was used as a base oil. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 18 mass ppm and the fullerene residual ratio was 0.18. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

[Example 12]
A lubricating oil composition was obtained in the same manner as in Example 4 except that 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide, which is an ionic liquid, was used as a base oil. As a result of measuring the fullerene concentration of the lubricating oil composition, it was 40 mass ppm and the fullerene residual ratio was 0.40. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

The comparison results of Examples 11 and 12 and Example 10 showed the same tendency as the comparison results of Examples 8 and 9 and Example 7 described above. That is, it was found that the ultraviolet irradiation treatment and the heat treatment are effective from the viewpoint of abrasion resistance effect and degassing reduction even in different ionic liquids.

[Example 13]
A lubricating oil composition was obtained in the same manner as in Example 1 except that the ionic liquid 1-butyl-4-methyl-pyridium bis (fluorosulfonyl) imide was used as the base oil. Table 1 shows the wear resistance of the obtained lubricating oil composition and the degree of desorption gas.

[Comparative Example 5]
A lubricating oil composition was obtained in the same manner as in Example 13 except that the raw material fullerene (without the sublimation step) was used as it was instead of the fullerene sublimated product. Table 1 shows the wear resistance and the degree of degassed gas of the obtained lubricating oil composition.

Comparing Example 13 and Comparative Example 5, the desorption gas degree before and after the wear resistance test was superior in Example 13 using the fullerene sublimated product. This was the same as the above-mentioned comparison result of Example 1 and Comparative Example 1 and the comparison result of Example 7 and Comparative Example 3. That is, it was found that it is effective to use a fullerene sublimated product from the viewpoint of reducing the degree of desorbed gas even if the base oil is different.

The present invention exhibits excellent wear resistance, has a low vapor pressure, can suppress an increase in vapor pressure due to deterioration of base oil, and maintains stable lubrication performance for a long period of time even under vacuum. It is possible to provide a lubricating oil composition capable of providing a lubricating oil composition.
The lubricating oil composition of the present embodiment is plastic processing such as industrial gear oil; hydraulic hydraulic oil; compressor oil; refrigerating machine oil; cutting oil; rolling oil, pressing oil, forging oil, drawing oil, drawing oil, punching oil and the like. Oil; Metal processing oil such as heat treatment oil and discharge processing oil; Sliding guide surface oil; Bearing oil; Rust preventive oil; Suitable for various oils such as heat transfer oil. In particular, it is suitable for use in a vacuum state, that is, as various oils used in a vacuum container provided in outer space or a vacuum device.

Further, the lubricating oil composition of the present invention is useful for devices and equipment used in high altitude regions and outer space. For example, long-term suppression of metal parts being damaged or worn under vacuum in sliding parts of equipment or devices mounted on aircraft, spacecraft, rockets, spacecraft, space stations, satellites, etc. Extremely useful for Further, the lubricating oil composition of the present invention includes a vacuum metallurgical apparatus for forging and joining, a vacuum chemical apparatus for performing chemical reactions, a vacuum thin film forming / processing apparatus for vapor deposition and sputtering, and an analyzer such as an electron microscope. Extremely useful for long-term suppression of scratches and wear on metal parts in sliding parts inside a vacuum vessel provided in a vacuum device such as a vacuum test device that performs bending, tension, compression tests, etc. Is.

Claims (16)

Contains fullerenes and base oils
The fullerene is a sublimated fullerene,
A lubricating oil composition in which the base oil is a multi-alkyl cyclopentane oil or an ionic liquid. Further containing a fullerene adduct,
The lubricating oil composition according to claim 1, wherein the fullerene adduct has a structure in which an adduct having a part of the molecular structure constituting the base oil is added to the fullerene. The method for producing a lubricating oil composition according to claim 1 or 2.
A method for producing a lubricating oil composition, which comprises a dissolution step of dissolving a fullerene sublimate in a base oil to obtain a fullerene solution. The third aspect of claim 3, further comprising a sublimation step of obtaining the fullerene sublimated product by sublimating the raw material fullerene in a non-oxidizing atmosphere to make it a gas and then cooling it to make it a solid before the melting step. A method for producing a lubricating oil composition. The method for producing a lubricating oil composition according to claim 3 or 4, wherein the fullerene sublimation product contains C ₆₀ , C _{70 or a mixture thereof.} The method for producing a lubricating oil composition according to any one of claims 3 to 5, further comprising a removing step of removing an insoluble component from the fullerene solution after the dissolution step. The production of the lubricating oil composition according to any one of claims 3 to 6, further comprising a heat treatment step of heat-treating the fullerene solution in a non-oxidizing atmosphere to form a fullerene adduct after the dissolution step. Method. The method for producing a lubricating oil composition according to claim 7, wherein the heat treatment temperature in the heat treatment step exceeds the upper limit temperature for use of the base oil and is in the range of the upper limit temperature for use + 200 ° C. or lower. The method for producing a lubricating oil composition according to claim 7, wherein the heat treatment temperature in the heat treatment step is 150 ° C. or higher and 300 ° C. or lower. After the dissolution step, the fullerene solution is further irradiated with radiation in a non-oxidizing atmosphere to form a fullerene adduct, further comprising a radiation treatment step.
The method for producing a lubricating oil composition according to any one of claims 3 to 6, wherein the radiation is ultraviolet rays or ionizing radiation. The method for producing a lubricating oil composition according to claim 10, wherein the radiation is ultraviolet rays having a wavelength of 190 nm or more and 365 nm or less. The method for producing a lubricating oil composition according to claim 10 or 11, wherein the amount of energy of radiation irradiated in the radiation treatment step is 1 J or more and 100 J or less per 1 mL of the fullerene solution. The method for producing a lubricating oil composition according to any one of claims 7 to 12, wherein the partial pressure of oxygen gas in the non-oxidizing atmosphere is 10 pascals or less. In the heat treatment step or the radiation treatment step, the concentration of fullerene in the fullerene solution is 0.1 times or more and 0.7 times or less with respect to the concentration of fullerene before the heat treatment step or the radiation treatment step. The method for producing a lubricating oil composition according to any one of claims 7 to 13, which is carried out up to. The method for producing a lubricating oil composition according to claim 14, wherein the treatment time of the heat treatment step or the radiation treatment step is 5 minutes or more and 24 hours or less. A vacuum apparatus including the vacuum container, wherein the lubricating oil composition according to claim 1 or 2 is used in the vacuum container.